local voucherId = ARGV[1]
local userId = ARGV[2]
local orderId = ARGV[3]

local stockKey = 'seckill:stock:' .. voucherId
local orderKey = 'seckill:order:' .. voucherId

if(tonumber(redis.call('get',stockKey)) <= 0) then
    --库存不足，返回1
    return 1
end
if(redis.call('sismember', orderKey, userId) == 1) then
    --存在，说明是重复下单，返回2
    return 2
end
redis.call('incrby', stockKey, -1)
redis.call("sadd", orderKey, userId)
redis.call('xadd','stream.orders','*','userId',userId,'voucherId',voucherId,'id',orderId)
return 0
